Combustor liner for a can-annular gas turbine engine and a method for constructing such a liner

ABSTRACT

A combustor liner ( 30 ) for a can-annular gas turbine engine ( 10 ) and a method for constructing such a liner are provided. The combustor liner includes an annular wall member ( 32 ) A cooling channel ( 34, 42, 50, 54, 56, 58 ) is formed through the wall member and extends from an inlet end of the liner to an outlet end of the liner A property of the cooling channel may be varied along a length of the cooling channel. The cooling channel may be formed through the combustor liner using an electro-chemical machining (ECM) process or a three dimensional printing process (3DP).

This application claims benefit of the 6 Feb. 2013 filing date of U.S. provisional patent application No. 61/761,367 which is incorporated by reference herein.

FIELD OF THE INVENTION

The present invention is generally related to gas turbine engines and, more particularly, to a combustor liner for a gas turbine engine, and a method for constructing such a liner

BACKGROUND OF THE INVENTION

Power generation systems, such as can-annular gas turbine engines, include sophisticated combustion components and processes for improving combustion efficiency. Market trends push for longer lifetime for components of the engine, reduced emissions of nitrogen oxides (NOx) and higher firing temperatures. Known combustor liners for can-annular gas turbine engines typically involve a pair of concentric rings, such as a plate with grooves and a sleeve which cooperate to direct cooling air to maintain appropriate liner temperatures at the combustor exhaust zone. These grooves are constructed using traditional machining techniques, and, consequently are not suited for structural refinements which would allow to more efficiently meeting thermal transfer demands along the combustor liner Thus, there continues to be a need for an improved combustor liner for a can-annular gas turbine engine, and a method for constructing such a liner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in the following description in view of the drawings that show.

FIG. 1 is a simplified schematic of a can-annular turbine engine, which may benefit from aspects of the present invention.

FIG. 2 is a cross-sectional view of one example embodiment of a combustor liner embodying aspects of the present invention.

FIG. 3 is an isometric view of a combustor liner, such as shown in FIG. 2.

FIG. 4 is a cross-sectional view of another example embodiment of a combustor liner embodying aspects of the present invention.

FIG. 5 is an isometric view of a combustor liner, such as shown in FIG. 4

FIG. 6 illustrates respective side views of example cooling channels embodying aspects of the invention.

FIGS. 7 and 8 illustrate respective cross-sectional shapes of cooling channels embodying other aspects of the present invention.

FIG. 9 illustrates further examples of cross-sectional shapes of cooling channels embodying aspects of the present invention

FIG. 10 is a flow chart of a method embodying aspects of the present invention for constructing a combustor liner for a can-annular gas turbine engine.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have innovatively recognized certain limitations in connection with known combustor liners for can-annular gas turbine engines. For example, structural limitations of known combustor liners may impede the ability to vary one or more properties of the cooling channel along a length of the cooling channel This ability would allow tailoring the cooling channel to more efficiently meet expected thermal transfer demands along the combustor liner In view of such recognition, the present inventors propose an innovative combustor liner for a can-annular gas turbine engine, and a method for constructing such a liner, where a cooling channel may be formed through the combustor liner using a process for forming a structure, such as may involve complex geometries and/or tightly-controlled tolerances In one non-limiting embodiment, the forming process may be based on subtraction of material, such as an electro-chemical machining (ECM) process In another non-limiting embodiment, the forming process may be based on addition of material, such as a three dimensional printing (3DP) process, also referred to as additive manufacturing

In the following detailed description, various specific details are set forth in order to provide a thorough understanding of such embodiments. However, those skilled in the art will understand that embodiments of the present invention may be practiced without these specific details, that the present invention is not limited to the depicted embodiments, and that the present invention may be practiced in a variety of alternative embodiments. In other instances, methods, procedures, and components, which would be well-understood by one skilled in the art have not been described in detail to avoid unnecessary and burdensome explanation.

Furthermore, various operations may be described as multiple discrete steps performed in a manner that is helpful for understanding embodiments of the present invention However, the order of description should not be construed as to imply that these operations need be performed in the order they are presented, nor that they are even order dependent unless otherwise so described. Moreover, repeated usage of the phrase “in one embodiment” does not necessarily refer to the same embodiment, although it may. Lastly, the terms “comprising”, “including”, “having”, and the like, as used in the present application, are intended to be synonymous unless otherwise indicated.

FIG. 1 is a simplified schematic of a gas turbine engine, such as a can-annular gas turbine engine 10. As will be appreciated by those skilled in the art, turbine engine 10 includes a compressor 12 for compressing air, a combustor 14 for mixing the compressed air with fuel and igniting the mixture. In practice, the turbine engine includes a plurality of annularly arranged combustors, which may be referred to in the art as combustor cans but just one combustor is shown in FIG. 1 for simplicity of illustration. FIG. 1 further illustrates a turbine section 16 where energy is extracted to turn a shaft 18, which may power the compressor 12 and auxiliary equipment, such as an electrical generator (not shown). Combustor 14 produces a hot-temperature flow (e.g., gases flowing at approximately 1700° C. or more), which passes from combustor 14 through a transition 15 and into turbine section 16.

In one example embodiment, as may be appreciated in FIGS. 2 and 3, a combustor liner 30 for a can-annular gas turbine engine comprises an annular wall member 32, which may be an integral member One or more cooling channels 34 are formed through the wall member 32 and may extend from an inlet end 36 of liner 30 to an outlet end 38 of the liner. In one example embodiment, the cross-sectional shape of a cooling channel 34 may be a generally rounded shape, such as circular, elliptical, or other shapes free of corners, and the channel may be aligned along a longitudinal axis 40 of the liner 30. The use of ECM or 3DP provides the ability to form cooling channels having a relatively large ratio of length to maximum cross-section dimension (L/D) with tightly controlled tolerances. For example, this provides the ability to form a relatively larger number of smaller-sized cooling channels per unit area, which is conducive to improve the heat transfer efficiency of the liner. In one example embodiment, cooling channels having an L/D ratio ranging from approximately 100 to approximately 200 may be implemented.

In one example embodiment, the use of ECM or 3DP may further provide the ability to vary a property of the cooling channel along the length of the cooling channel. For example, as illustrated in FIGS. 4 and 5, a circumferential position of a cooling channel 42 may vary along the longitudinal axis 40 of the liner 30 In one example embodiment, the cooling channel 42 may be configured to define a curve in the three-dimensional wall member, such as a helix shape This configuration effectively increases the surface area available per cooling channel compared to a cooling channel which is aligned along the longitudinal axis of the liner.

Further examples of respective cooling channel properties that may be varied along the length of the cooling channel through the use of ECM or 3DP may be as conceptually illustrated in FIG. 6. For example, a diameter of a cooling channel 50 is not constant along its length. In another example, a surface finish of a cooling channel 52 is not constant along its length For example, an inner surface portion 54 of cooling channel may have a surface finish comprising a relatively coarser surface finish compared to other inner surface portions of the channel. As will be appreciated by one skilled in the art, this type of structural features may effectively provide along the length of the cooling channel, turbulence zones having a locally-enhanced heat transfer capability.

FIGS. 7 and 8 illustrate respective cross-sectional shapes of cooling channels embodying further aspects of the present invention. For example, the use of ECM or 3DP further provides the ability to form cross-sectional shapes that may comprise respective multi-lobe shapes, such as conceptually illustrated for cooling channels 56, 58. This type of cross-sectional shape may be effective to increase the wetted area and thus the available heat transfer area per cooling channel compared to a cooling channel with a discrete rounded shape Moreover, structural features of such multi-lobe shapes need not be constant along the length of the cooling channel. For example, the size of one or more of the lobes may be adjusted along the length of the cooling channels depending on the heat transfer demand at a given liner location.

FIG. 9 further illustrates further examples of cross-sectional shapes that may be feasible for the cooling channels through the use of ECM or 3DP. For example, cross-sectional shapes having corners, such as square 60, rectangular 62, triangular 64, polygonal shapes 66, etc may be implemented.

FIG. 10 is a flow chart 100 of a method for constructing a combustor liner for a can-annular gas turbine engine In one example embodiment, subsequent to a start step 102, a step 104 allows establishing expected thermal transfer demands along the combustor liner. For example, the expected thermal transfer demands may be obtained by collection of historical data, modeling, experimentation or any suitable means for acquiring information indicative of the expected thermal transfer demands along the combustor liner. A step 106 allows forming a cooling channel through the combustor liner using a process for forming a structure, such as may involve complex geometries and/or tightly-controlled tolerances. Non-limiting embodiments of the forming process may be based on subtraction of material, such as an electro-chemical machining (ECM) process; or, alternatively, the forming process may be based on addition of material, such as a three dimensional printing (3DP) process Prior to a return step 110, a step 108 allows controlling the forming process to vary a cooling channel property along a length of the cooling channel based on the expected thermal transfer demands For example, the cooling channel property may be varied to meet a relatively higher thermal transfer demand at a given location of the liner.

While various embodiments of the present invention have been shown and described herein, it will be apparent that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims. 

The invention claimed is:
 1. A combustor liner for a can-annular gas turbine engine comprising. an annular wall member; and a cooling channel formed through the wall member and extending from an inlet end of the liner to an outlet end of the liner, wherein a property of the cooling channel varies along a length of the cooling channel.
 2. The combustor liner of claim 1, wherein a circumferential position of the cooling channel varies along a longitudinal axis of the liner
 3. The combustor liner of claim 2, wherein the cooling channel defines a curved shape
 4. The combustor liner of claim 2, wherein the cooling channel defines a helix shape.
 5. The combustor liner of claim 1, wherein a diameter of the cooling channel is not constant along its length.
 6. The combustor liner of claim 1, wherein a surface finish of the cooling channel is not constant along its length
 7. The combustor liner of claim 1, wherein a cross-sectional shape of the cooling channel is not constant along its length.
 8. The combustor liner of claim 1, wherein a cross-sectional shape of the cooling channel comprises a multi-lobe shape.
 9. A combustor comprising the combustor liner of claim
 1. 10. A method for constructing a combustor liner for a can-annular gas turbine engine, the method comprising: establishing expected thermal transfer demands along the combustor liner; forming a cooling channel through the combustor liner using a process for forming a structure; and controlling the forming process to vary a cooling channel property along a length of the cooling channel based on the expected thermal transfer demands.
 11. The method of claim 10, wherein the forming process comprises an electro-chemical machining process.
 12. The method of claim 10, wherein the forming process comprises a three-dimensional printing process
 13. The method of claim 10, further comprising varying a circumferential position of the cooling channel along a longitudinal axis of the liner.
 14. The method of claim 13, wherein the cooling channel defines a helix shape
 15. The method of claim 10, further comprising controlling the forming process such that a diameter of the cooling channel is not constant along its length.
 16. The method of claim 10, further comprising controlling the forming process such that a surface finish of the cooling channel is not constant along its length.
 17. The method of claim 10, further comprising controlling the forming process such that a cross-sectional shape of the cooling channel is not constant along its length
 18. The method of claim 10, further comprising controlling the forming process such that a cross-sectional shape of the cooling channel comprises a multi-lobe shape
 19. A combustor liner for a can-annular gas turbine engine comprising. an annular wall member, and a cooling channel formed through the wall member and extending from an inlet end of the liner to an outlet end of the liner, wherein a property of the cooling channel varies along a length of the cooling channel, and wherein the cooling channel is formed by a process selected from the group consisting of an electro-chemical machining process and a three-dimensional printing process. 